Final answer:
Industrial air washers are best installed at the suction side of the supply fan to clean the air before it passes through the fan and HVAC system, ensuring equipment protection and improved indoor air quality.
Step-by-step explanation:
Industrial air washers should be installed at the suction side of the supply fan. This location ensures that the air is cleaned before it goes through the fan and other components of the HVAC system, helping to protect the equipment and improve indoor air quality. Positioning the air washer on the suction side helps to remove contaminants from the air efficiently, preventing them from accumulating within the system and potentially being dispersed into the occupied space after the supply fan.